Method, apparatus, and system for air-conditioning with dehumidification

ABSTRACT

Embodiments comprise methods and arrangements for cooling and dehumidifying outgoing air. Embodiments may comprise a temperature sensor to couple with an air conditioning controller to cycle a fan for conditioned air to increase dehumidification of the conditioned air. Some embodiments comprise a temperature sensor coupled with the low pressure side return line and the fan to turn the fan on and off. In some embodiments, the temperature sensor may comprise logic to control a duty cycle of the fan. Some embodiments comprise a very low cost substitute for a continuously variable speed fan in the condenser unit to turn on the evaporator unit blower as needed and turn the blower off, e.g., roughly for half of every one minute, or turn the blower to low speed if the fan motor has a low speed wiring. Such arrangements may be installed as original equipment or as a retrofit.

BACKGROUND

The present invention is in the field of air conditioners (A/Cs), and more specifically in the field of cooling systems that achieve more air dehumidification.

Standard A/C units are not designed to produce the lowest easily achievable humidity. To meet requirements for greater Seasonal Energy Efficiency Ratio (“SEER”) efficiency, coil designers have increased the airflow rate and coil size (not its thickness to area ratio) to assure transfer of all available cooling from the refrigerant to the air. The unfortunate consequence is that humidity may be even higher with higher SEER units.

The amount of cooling energy generally required by an A/C is equal the amount of cooling required to remove the heat produced in the air conditioned space by people, appliances etc., plus an amount of cooling required to balance the heat flow into the space through the space enclosure (walls, windows, ceiling floor etc.) plus heat carried in with infiltrating air. Heat inflow is typically far greater than internally generated heat, especially in older residential buildings. And due to the fact that an apartment resident or office occupant will feel equally comfortable at a higher temperature setting if the humidity is lower; reducing humidity in an air conditioned space will save heat inflow related energy costs.

In a normal A/C, the fan speed is constant and must be high enough to cover all expected operating conditions. The highest air flow is required when the coil and/or filter have become somewhat dirty, when the evaporator coil has lost efficiency with age, and when cooling to a relatively low room temperature. The fan power must be large enough to cover the rare possibility that all these occur simultaneously.

Refrigeration air-conditioning equipment, the typical household or office A/C, reduces the humidity of the air processed by cooling the inside air below the dew point. The colder the air is cooled, as it passes through the A/C coils, the greater the moisture removal and lower the indoor humidity at a given indoor temperature. As anyone who has been in both the desert and tropics knows, it doesn't feel as hot when the humidity is low. Our tests in actual lived-in apartments show that at 40% relative humidity (RH) a temperature of 80-85° F. feels as comfortable as 72° F. at 65% RH.

A specific type of air conditioner that is used only for dehumidifying is called a dehumidifier. A dehumidifier is different from a regular air conditioner in that both the evaporator and condenser coils are placed in the same air path, and the entire unit is placed in the environment that is intended to be conditioned (in this case dehumidified), rather than requiring the condenser coil to be outdoors. Having the condenser coil in the same air path as the evaporator coil produces warm, dehumidified air. The evaporator (cold) coil is placed first in the air path, dehumidifying the air exactly as a regular air conditioner does. The air next passes over the condenser coil re-warming the now dehumidified air. Note that the terms “condenser coil” and “evaporator coil” do not refer to the behavior of water in the air as it passes over each coil; instead they refer to the phases of the refrigeration cycle. Having the condenser coil in the main air path rather than in a separate, outdoor air path (as in a regular air conditioner) results in two consequences—the output air is warm rather than cold, and the unit is able to be placed anywhere in the environment to be conditioned, without a need to have the condenser outdoors.

Unlike a regular air conditioner, a dehumidifier will actually heat a room. The amount of heating is the same as an electric heater of the same wattage. A regular air conditioner transfers energy out of the room by means of the hot condenser coil, which is outside the air-conditioned space (e.g., outdoors).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an embodiment of an air-conditioning (A/C) system;

FIG. 2 depicts an embodiment of a system to switch a fan (blower) of an air conditioning system between fan speed states;

FIG. 3 depicts an embodiment of an installed apparatus to switch a fan of an air conditioning system between two fan speed states;

FIG. 4 depicts an alternative embodiment of an installed apparatus to switch a fan of an air conditioning system between three fan speed states;

FIG. 5 illustrates an embodiment of a flow chart for cycling the blower of an air conditioning system; and

FIG. 6 illustrates an embodiment of a flow chart for installing a retrofit for cycling the fan of an air conditioning system.

DETAILED DESCRIPTION OF EMBODIMENTS

The following is a detailed description of novel embodiments depicted in the accompanying drawings. However, the amount of detail offered is not intended to limit anticipated variations of the described embodiments; on the contrary, the claims and detailed description are to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present teachings as defined by the appended claims. The detailed descriptions below are designed to make such embodiments understandable to a person having ordinary skill in the art.

INTRODUCTION

Generally, air-conditioning with dehumidification is described herein. Embodiments cycle the fan, or blower, of conditioned air of the air conditioning system to increase dehumidification of the conditioned air. Some embodiments comprise a temperature sensor coupled with the low pressure side return line, also referred to as a low side line, that returns coolant from the evaporative unit to the condenser unit of an air conditioning system. Such embodiments interconnect the temperature sensor with the fan for the conditioned air to cycle the fan between more than one fan states. For instance, in response to instructions from an air conditioner controller to turn on the fan, many embodiments cycle the fan on and off. Other embodiments cycle the fan between a high fan speed and a low fan speed or a high speed fan state, a low speed fan state, and a fan off state. Further embodiments may include a fan with more than three speed states and some of such embodiments may include a variable speed fan.

In several embodiments, the fan is cycled on and off based upon the temperatures indicated by the temperature sensor. Power for the fan may be switched via a relay to turn the fan on in a high speed fan state in response to a high threshold temperature and to place the fan in a second fan state in response to a low threshold temperature. In some embodiments, the second fan state may be a fan off state or, in other words, may be a state in which the fan is turned off. In other embodiments, the second fan state may be a state in which the fan operates at a low fan speed.

Many embodiments include logic communicatively coupled with the temperature sensor. The logic may monitor the temperatures of the return line to determine when to cycle the fan. The logic may be included to minimize hysteresis involved with cycling the fan between fan states, to determine thresholds for changing between one or more different fan states, to protect the fan from damage as a result of cycling the fan between states, to increase the efficiency of the fan by reducing the power consumed by the fan to transfer heat from the air conditioned space to the evaporative coils, and to determine the amounts of time the fan should reside in one or more different states. For example, in some embodiments, the logic may compare temperatures with one or more threshold temperatures or measure time periods and cycle the fan according to one or more time periods. In other embodiments, logic may learn or adapt time periods or temperatures based upon measurements of time and/or temperatures to improve the performance of the air conditioning system toward one or more predetermined or settable performance goals.

In some embodiments, the logic determines a “second fan state” time, which is referred to as a fan-off time for embodiments in which the second fan state is a fan off state. The second fan state time is the amount of time that the fan should remain in the second fan state or off to let the cooled coolant to enter the evaporative coil. In other words, the second fan state time is an amount of time to leave the fan in the second fan state to allow cooled coolant from the condenser resulting from the fan being in the second fan state to build up in the evaporative unit but not leave the evaporator coils while still cold. For example, an efficient time frame for leaving the fan off may be 30 seconds. While the fan is off, the coolant may cool to much colder temperatures, e.g., about 32° F. from about 73° F. to 61° F. By the time the cooled coolant reaches the low pressure side return line, the cooled coolant is returning the to compressor, degrading the efficiency of the system. So the logic may determine that the cooled coolant reaches the temperature switch at 30 seconds from the time the fan is turned off and, in response, turn on the fan ten seconds earlier or at 20 seconds from the time the fan was turned off.

With the determination of a second fan state time, the logic may determine a duty cycle to impose on the fan while the fan is turned on by the air conditioner controller. In some embodiments, the logic may simply include one or more default duty cycles and, in some of these embodiments, a default duty cycle may be implemented by a default setting for a dip switch coupled with the logic. In further embodiments, a user may select between the more than one duty cycles by other means.

The optimal second fan state times may depend upon the air conditioning system cycle, the coolant in use, and environmental conditions but the logic, in some embodiments, can adjust the second fan state time to maintain the system near or at the optimal second fan state time by adjusting the second fan state time based upon temperature readings from the temperature sensor and the timing of the temperature readings from the temperature sensor. For example, the optimal second fan state time may be the optimal fan-off time if the second fan state is the state at which the fan is off or powered off. The optimal fan-off time may be, for instance, around 20 seconds. Depending upon the air conditioning system and other factors, the optimal fan-off time may be between 15 and 25 seconds, between 10 and 30 seconds, or between 10 and 40 seconds. Furthermore, the optimal drop in temperature at the return line, also referred to as a threshold temperature change, may be between 5° F. and 17° F., between 8° F. and 15° F., or be at or around 12° F. So the logic may default to selection of a proportion of the fan-off time such as 70% or 75% of the fan-off time prior to turning on the fan. Further embodiments may reduce the fan-off time by a predetermined amount of time such as 15 seconds to determine the optimal fan-off time. When the fan is turned off, the logic may measure the time between system turning off the fan and the return line dropping by a threshold temperature change such as, e.g., 12° F. The fan will be turned on in response to the temperature dropping 12° F. or reaching a low temperature threshold. Then the fan-off time measured will be reduced to about 70% of the measured fan-off time.

The reduction of the fan-off time will cause the fan to force air across the evaporative coils prior to the cooled coolant reaching the return line, which warms the coolant before the coolant reaches the return line. The logic may then monitor the timing of the drop in the temperature of the coolant in the return line. For example, the cooled coolant may reach the return line 12 seconds after the fan is turned on. Based upon this determination, the logic may adjust the fan-off time by a couple seconds so that the drop in temperature of the coolant at the return line occurs 10 seconds after the fan is turned on. In some embodiments, the logic may determine a desired fan-off time or second fan state time based upon the timing of the temperature drop of the return line.

In further embodiments, the logic may take into consideration the temperature drop at the return line in addition to the amount of time between turning on the fan and the temperature drop. For instance, the logic may determine that at 12 seconds from turning on the fan, the return line drops by 8° F. rather than 12° F. due to the reduction in the fan-off time. The logic may employ an algorithm to find a desired balance between the temperature drop and the timing of the drop in temperature such as, e.g., 10 seconds and 12° F. Such an algorithm may estimate a preferred second fan state time or fan-off time once, continue to estimate the time based upon the current timing and temperature drop, or refine the estimate based upon the current timing and temperature drop and one or more prior timings and temperature drops.

In several embodiments, the logic may maintain the timing of the drop in temperature at the return line after the fan is turned on and the temperature drop at the return line within a predetermined temperature range. In other embodiments, the logic may maintain the timing of the temperature drop within a time range rather than both the timing and the temperature drop. In still other embodiments, the logic may maintain the temperature drop at the return line within a range rather than both the timing and the temperature drop.

In further embodiments, multiple fan speeds may be implemented in the cycle or the fan speed may be incrementally decreased toward no speed and/or incrementally increased toward the high fan speed. For example, the fan may be turned on in response to a signal from the air conditioner controller by applying a voltage to a yellow wire output for the controller, a temperature sensor may couple with the fan controller to cycle the fan to the high fan speed state from the second fan speed state in response to a low threshold temperature of, e.g., 40 degrees Fahrenheit (40° F.) or below and cycle the fan to the second fan speed state from the high fan speed state in response to a high threshold temperature of, e.g., 65° F. or above. In many of these embodiments, the temperature sensor couples with logic to refine the timing of switching between states such as between the high fan speed state and the second fan speed state.

In some embodiments, the temperature sensor may be installed in contact with the return line and may measure the temperature of the coolant by measuring the temperature of the return line.

Embodiments may also comprise a fan switch coupled with the temperature sensor. The fan switch may switch the fan between different fan speeds or may switch the fan off. In several embodiments, the fan switch may form part of the control circuit of the fan controller or part of the fan controller for the fan. In such embodiments, the temperature sensor may couple with the fan switch of the fan controller to change fan speeds. In other embodiments, the fan switch may be added along with the temperature sensor to an existing air conditioning system. In many embodiments, the fan switch may comprise a relay interconnected with the fan between the fan controller and the fan.

Some embodiments comprise an air conditioning system with logic to establish a duty cycle for the fan based upon the temperature of the coolant in the return line. Some embodiments comprise an apparatus coupled with an existing air conditioning system to establish a duty cycle for the fan based upon the temperature of the coolant in the return line. Further embodiments comprise a process of cycling the fan speed for expelling conditioned air of the air conditioning system. Other embodiments comprise a process for installing hardware for cycling the fan speed for expelling conditioned air of the air conditioning system.

Some embodiments comprise a very low cost substitute for a continuously variable speed fan in the A/C condenser unit obtainable by installation of a thermostat on the low pressure side return line and use of that thermostat to turn on the evaporator unit fan as needed and turn the fan off, e.g., roughly for half of every one minute, or turn the fan to low speed if the fan motor has a low speed wiring. Such arrangements may be installed as original equipment or as a retrofit. Some of these embodiments include logic to adjust the timing of turning the fan off for, e.g., half of every minute.

While some of the specific embodiments described below will reference the embodiments with specific configurations, those of skill in the art will realize that embodiments of the present disclosure may advantageously be implemented with other configurations with similar issues or problems. For instance, many descriptions of the embodiments described herein may refer to large air conditioner units but also apply to other embodiments comprising window mounted, automotive, and portable air-conditioning units or portions thereof. Further embodiments are illustrated in configurations that are more amenable to large units but variations of such configurations can be implemented as window mounted, air-conditioning systems.

FIG. 1 shows an embodiment of the components of an air-conditioning (A/C) system 100. The A/C system 100 may comprise a window air-conditioning unit, a portable A/C unit in which the outdoor unit is connected to an “outdoor” area via tubing, a central A/C system for a single family residence, a multiple-family residence, a commercial building, an office building, or an industrial building, or the like.

A/C system 100 may implement methods that involve a heat exchanger or heat exchange unit comprising one or more evaporation (cooling) units referred to as evaporative unit 134. The evaporative unit 134 has the refrigerant, such as R22 or other coolant. The airflow rate may be cycled to produce both cold (dehumidified) exit air and warmed exit coolant (for high efficiency). A device such as an expansion valve 120 may have a primary responsibility to assure that the coils are cold but not freezing although there is some interplay between air speed and icing of the evaporative unit 134. This may produce low humidity even when the room thermostat is set warm (e.g. 85° F.) which may result in 5%-25% to lower energy usage for the A/C system 100 and, thus, 5%-25% lower energy bills.

Some embodiments of A/C system 100 may be a standard A/C system that has been retrofitted. Such retrofits may involve adding a temperature sensor and, in some embodiments, adding a temperature sensor with logic 135 and a fan switch 142.

Retrofitting the A/C system 100 may also involve coupling temperature sensor with logic 135 to a return line 122, also referred to as the low pressure side return line, of the coolant between the evaporative unit 134 and a compressor 116, coupling the temperature sensor with logic 135 to a controller such as air-conditioner controller 160 or a fan controller 144 in indoor unit 130 to adjust or cycle a rate of airflow across coils of the evaporative unit 134, and coupling the controller with a fan 146 of an air unit 140 to adjust the rate of airflow across the evaporative unit 134.

In many embodiments, A/C system 100 may comprise an override logic 163 to allow for higher humidity. A/C system 100 could be configured to produce a desired (as input into A/C controller 160) humidity, e.g., by adjusting a duty cycle of cycling of fan 146, by adjusting the low threshold temperature and/or high threshold temperature for cycling fan 146, by adjusting a time period or time frame related to the optimal second fan state time, and/or by adjusting a temperature drop associated with the return line.

In some embodiments, A/C system 100 is designed to achieve lower humidity for applications such as low-income apartments, where occupants typically set the temperature uncomfortably high to save on A/C costs and where a standard A/C does not, in such conditions, provide sufficient dehumidification. The estimated savings may range from about 5% to 15% reduction in relative humidity with a reduction of total energy consumption of about 5% to 15%.

While the A/C system 100 illustrates a single outdoor unit 110 and a single indoor unit 130, other embodiments may comprise multiple indoor units and/or multiple outdoor units. For instance, a single outdoor unit may service more than one indoor unit. Furthermore, the following discussion implements a vapor compression refrigeration cycle but other refrigeration cycles are employed in alternative embodiments.

The coolant lines 121 and 122 connect the outdoor and indoor units 110 and 130 of the A/C system 100 via connections or couplings on the units 110 and 130 or on components within the units 110 and 130 and may comprise, e.g., copper tubing, aluminum tubing, rubber tubing with a steel mesh jacket, plastic tubing such as polyvinyl chloride (PVC) tubing, or other appropriate interconnections. The couplings or connections may comprise fittings designed for the particular type of tubing utilized and the type and temperatures of the coolant.

The outdoor unit 110, also referred to as a condenser unit, may comprise a fan 112, condenser coils 114, a compressor 116, and a control panel 118. Incoming liquid refrigerant such as R22 or other coolant may be received in a saturated vapor state at the outdoor unit 110 via a low pressure side return line 122. The saturated vapor coolant may be compressed via compressor 116 to a superheated vapor state. The superheated vapor coolant is transported to the condenser coils 114. As the superheated vapor coolant is transported through the condenser coils, fan 112 may pull or push air across the condenser coils 114 to condense the superheated vapor coolant to a saturated liquid state. Note that either an expansion valve 120 or capillary tubing is placed between the condenser coil and the low pressure, evaporative unit 134 to maintain sufficient back pressure on the compressor 116 for the compressor 116 to liquefy the coolant in the outside condenser coils 114. After the capillary tubing/expansion valve, the pressure is low enough that the refrigerant boils at roughly 0 to 10° C.

The expansion valve 120 abruptly reduces the pressure of the coolant causing an adiabatic flash evaporation of a part of the saturated liquid coolant, which lowers the temperature of the coolant and changes the coolant to a liquid and vapor mixture. The liquid and vapor mixture of coolant enters the evaporative unit 134, inside the indoor unit 130.

The indoor unit 130 comprises a return air duct 138 to receive air from an air conditioned space and an air unit 140 to establish the airflow rate of the air entering from the return air duct 138 through or over the evaporative unit 134 and out the conditioned air duct 136 to the air conditioned space. In many embodiments, indoor unit 130 may also include other modules such as heater modules, air filtration modules, air ionization modules, humidification modules, or the like.

Air unit 140 is designed to establish the airflow rate through the evaporative unit 134. In many embodiments, the air unit 140 may be controlled primarily via A/C controller 160. In many embodiments, the temperature sensor with logic 135 may cycle the fan 112 between two or more fan states. In some embodiments, more than one fan speed is provided. In other embodiments, the fan 146 may be on or off.

The A/C controller 160 may generate a signal such as by applying a voltage to a wire such as a yellow wire to instruct a fan controller 144 to turn on the fan 146 at a high fan speed. In response to the signal, the temperature sensor 135 and the fan switch 142 may cycle the fan 146 between a high-speed fan state and a second fan state. The high-speed fan state may turn on the fan 146 via the fan controller 146 at a high fan speed. The second fan state may turn off the fan 146 via the fan controller 144. In other embodiments, the second fan state may be a low speed state that turns on the fan 146 at a low fan speed, which is a speed that is lower than the high fan speed such as 80% of the high fan speed or 20% of the high fan speed. In such embodiments, the low fan speed may be adjusted during a retrofit process to another appropriate speed such as 10%, 30%, or 60% of the high fan speed based upon the configuration of the retrofit kit and possibly other factors.

In further embodiments, the fan 146 may be a variable speed fan. In such embodiments, the high speed fan state may be a default or selectable, high fan speed and the second fan state may be a default or selectable, low fan speed that may also include a no speed or zero speed in which, e.g., power may be disconnected from fan 146.

In many embodiments, the temperature sensor with logic 135 may comprise a bi-metallic switch thermally connected with the return line 122. In one embodiment, while the A/C controller 160 generates the signal to turn on the fan, the temperature sensor with logic 135 may trigger the fan switch 142 to be in a closed state while the temperature sensor with logic 135 is in the open switch state and the temperature sensor with logic 135 may cause the fan switch 142 to be in an open switch state while the temperature sensor 135 is in a closed state. In another embodiment, the open circuit state of the temperature sensor with logic 135 may cause the fan switch 142 to be in an open switch state while the closed circuit state of the temperature sensor with logic 135 may trigger the fan switch 142 to be in the closed switch state.

In other embodiments, the temperature sensor with logic 135 may comprise a multiple pole, bi-metallic switch, also referred to as a double-throw, bi-metallic switch, that comprises more than one closed position or multiple single pole, bi-metallic switches. Furthermore, some embodiments with a bi-metallic switch comprise a heat generator proximate to the switch to adjust temperature thresholds of the temperature switch and increase the switching speed of the bi-metallic switch. In further embodiments, a heat generator may apply heat to the temperature sensor with logic 135 via conduction, convection, and/or radiation in response to a change in state of the switch to reduce hysteresis lag time.

In further embodiments, the temperature sensor with logic 135 may comprise a solid-state temperature sensor such as a thermistor, a thermocouple, a solid-state temperature sensor such as a solid-state thermometer, or the like. A solid-state temperature sensor may comprise one or more integrated circuits in one or more chip packages. In some embodiments, the temperature sensor with logic 135 may reside on a single die with the fan switch 142 and in other embodiments, the temperature sensor with logic 135 may reside on a separate die than the fan switch 142 but reside within the same package. In other embodiments, the temperature sensor with logic 135 may comprise a separate package from the fan switch 142.

In many embodiments, the temperature sensor with logic 135 may comprise logic integrated with, connected to, connected with, or otherwise communicatively coupled with a temperature sensor. The logic may monitor and anticipate temperatures of the low pressure side return line 122 to determine when to cycle the fan 146. The logic may determine an amount of time that the fan spends in a high speed fan state and an amount of time the fan spends in one or more other fan states such as a second fan state. For purposes of clarity, most of the discussions will describe selection between two different fan speed states but embodiments may determine amounts of time in more than two fan speed states. For instance, the fan 146 may have three different speed states including a high speed fan state, a low speed fan state, and a fan off state. Based upon the timing between changes in temperature in the return line 122 after the fan is turned to the off state, the logic may change the fan 146 from the off state to the low speed state 5 or 10 seconds prior to turning the fan 146 to the high speed state. In other embodiments, the logic may change the state of the fan 146 from the off state to the low speed state in response to a small change in the temperature of the coolant in the return line 122 such as a 5° F. change or a 10° F. change. Similarly, the logic may change the state of the fan 146 from the low speed state to the high speed state within a time period from a change from the off state to the low speed state or from a change from an on state to the off state. Or the logic may change the speed of the fan 146 from state to state based upon a temperature change, or some combination of temperature change and elapsed time since a prior change in state. For example, the state of the fan 146 may be changed to the high speed fan state in response to a temperature change after a time period has elapsed since the last or a prior change in speed state of the fan 146. In some embodiments, the time period may be implemented to protect the fan 146 from damage or to increase the efficiency of the fan 146.

One “second fan state” time is referred to as a fan-off time because the second fan state is a fan off state for the fan 146. The second fan state time is the amount of time that the fan 146 should remain in the second fan state or off to let the cooled coolant to progress toward the return line 122 from the compressor 116. For example, an efficient time frame for leaving the fan 146 off may be 20 seconds. While the fan 146 is off or in a low speed state, the coolant may cool by, e.g., 15° F. from about 75° F. to 60° F. The logic may determine, based upon timing of prior temperature readings, that the cooled coolant reaches the temperature sensor with logic 135 at 30 seconds from the time the fan 146 is turned off and, in response, the logic may turn on the fan 146 five to ten seconds before the cooled coolant reaches the return line 122.

The logic may adjust cycling of the fan 146 or, in some embodiments, a duty cycle imposed on the fan 146, based upon temperature readings from the temperature sensor and the timing of the temperature readings from the temperature sensor. In some embodiments, the logic may determine a time at which the fan 146 is turned off or to a low speed state and may apply a duty cycle pattern stored within or integrated with the logic. For example, one or more duty cycle patterns may be integrated with the logic, built into the logic, stored in the logic, or stored in memory coupled with the logic. The duty cycles may be designed for specific air conditioner types, sizes, installations, environments, etc., and/or a combination of one or more of these factors.

Upon identifying the time at which the fan 146 is turned on, the logic may initiate cycling of the fan 146 or apply a duty cycle to the fan 146. For embodiments in which the logic is designed to impose one duty cycle, such as when the temperature sensor with logic 135 is designed for a specific air conditioner type, that duty cycle may be applied. For embodiments in which the logic is designed to impose multiple duty cycles, the logic may default to a particular duty cycle and another duty cycle may be selectable. In several embodiments, an installing technician may select the appropriate duty cycle based upon the air conditioner type, the installation type, the environmental conditions, or other factors, or the technician may cycle through one or more duty cycles to determine which duty cycle is most appropriate through testing. In some embodiments, the technician may select a duty cycle and/or adjust a duty cycle by adjusting a dip switch, rheostat, or the like of the temperature sensor with logic 135 or coupled therewith.

In another embodiment, the logic may test one or more duty cycles and measure the timing of temperature changes and temperatures to determine the most appropriate cycle for a particular air conditioning system such as air conditioning system 100. For example, the temperature sensor with logic 135 may apply various duty cycles, and select the duty cycle that most closely matches a desired pattern of temperature readings and timing. The desired temperature readings and timing may be built into the logic or in memory coupled with the logic and may be a general pattern for a particular air conditioning system, installation, and/or environment, or may be for a group of systems, installations, and/or a range of environments. In other embodiments, the logic may try different duty cycles until the timing and/or temperatures fall within an acceptable range. Changes in the duty cycle may change the location of the cooled coolant at which the fan 146 is placed in the high speed fan state to force air across the evaporative coils of the evaporative unit 134, which may be prior to the cooled coolant reaching the return line 122.

In further embodiments, the logic may monitor the temperature change and timing prior to implementing a duty cycle and select or establish the duty cycle based upon the temperature change and timing. For example, the logic may monitor the timing of the drop in the temperature of the coolant of about 10° F. in the return line 122. The cooled coolant may reach the return line 32 seconds after the fan is turned off. Based upon this determination, the logic may select or establish a duty cycle with a fan-off time of about 22 seconds based upon an acceptable time period being 8 to 12 seconds and a temperature drop being between 8° F. and 15° F. Some of these embodiments will set this duty cycle and not change the duty cycle unless the temperature sensor with logic 135 is reset. Other embodiments may verify the duty cycle by comparing a subsequent temperature change and timing to those accessible by the logic. For instance, the logic may look up a duty cycle based upon the temperature change and timing. In further embodiments, the logic may look up the duty cycle based upon the temperature change and timing as well as other factors indicated by, e.g., settings of a dip switch.

In several embodiments, the logic may cycle the fan 146 based upon the timing of the drop in temperature at the return line after the fan is turned on and the temperature drop at the return line being within a temperature range. In other embodiments, the logic may cycle the fan 146 based upon the timing of the temperature drop being within a time range rather than based upon both the timing and the temperature drop. In still other embodiments, the logic may cycle the fan 146 based upon the temperature drop at the return line being within a range rather than based upon both the timing and the temperature drop.

A solid-state temperature sensor may provide for faster cycling between the high-speed fan state and the second fan state, than a bi-metal switch. In such embodiments, the temperature sensor 135 may couple with a fan switch 142 that comprises a solid-state relay, which may be in the same integrated circuit chip as the temperature sensor. Furthermore, if the solid state switch is mounted on a cold A/C line, along with or integrated into the same chip as the temperature sensor, then the A/C coolant line acts as a cold heat-sink and allows for a smaller size chip.

Fan 146 may comprise an electric motor that is characterized by a locked rotor current. The locked rotor current may be a transient, high current drawn by the motor when the motor is first energized because the windings of the electric motor initially present very little resistance to A/C current. This locked rotor current heats the windings of the electric motor significantly. Thus, some embodiments impose a maximum number of on/off cycles per time.

Embodiments may comprise any known configuration of cooling coils. For example, some embodiments, includes slab coils A-frame coils and zig-zag coils.

Further embodiments comprise an override temperature sensor 137 or other ice detection sensor, which disables the fan motor cycling by the temperature sensor with logic 135, if the coils begin to ice up. The override temperature sensor 137 may reside on or near the evaporative unit 134.

In some embodiments, the compressor 116 may comprise a variable speed compressor and A/C controller 160 or logic of control panel 118 may control the speed of the compressor 116. Such embodiments may comprise logic to reduce the speed of the compressor 116 to adjust the refrigeration cycle to de-ice the evaporative unit 134 or to avoid ice build-up or additional ice build-up on evaporative unit 134.

The A/C controller 160 may comprise controller logic 162 as well as inputs and outputs and a user interface to receive information from a user regarding how to control the ambient room temperature or the sensed or perceived temperature based upon the actual ambient temperature in a conditioned room and the humidity. In some embodiments, the A/C controller 160 may comprise a processor-based controller or other intelligent/sophisticated controller to maintain the conditioned air temperature. In one embodiment, air conditioner controller 160 may receive temperature readings from the temperature sensor with logic 135 and control the fan switch 142 based upon the temperature readings to vary fan speed and, in some embodiments, louver positions, to vary airflow rates through the evaporative unit 134.

The controller logic 162 may comprise hardware, code, or a combination of hardware and code such as a processor and memory for executing software or firmware on a storage medium. The A/C controller 160 may be settable to maintain a user specified temperature and user specified humidity, a user specified wet bulb temperature or in-between-point between the wet and dry bulb temperature or the A/C may simply dehumidify, e.g., as much as it can or some portion thereof, and the user will set only the temperature.

FIG. 2 depicts an embodiment of an apparatus 200 to establish a duty cycle for a fan 270, or blower, of an air conditioning system such as the air conditioning system 100 in FIG. 1. The apparatus 200 comprises an A/C controller 210, wiring 221-224, a temperature sensor 240, logic 247, a fan switch 250, a fan controller 260, and the fan 270. For example, the A/C controller 210 may be an interface for a user to adjust the functionality of the air conditioning system in accordance with the user's preferences. The A/C controller 210 may turn on and off heating or cooling based upon temperature settings that are either default or that are input by the user. The A/C controller 210 may turn on the cooling and a fan 270 to distribute cool air into an air-conditioned space.

The A/C controller 210 may comprise a temperature sensitive switch 212 and a heat/cool switch 214. The temperature sensitive switch 212 may determine if cooling should be initiated based upon temperature settings for cooling and based upon the state of the heat/cool switch 214. For example, if the heat/cool switch is set to a cool state and the temperature sensitive switch 212 determines that or responds to the ambient temperature about a sensor of the temperature sensitive switch 212 rising above a temperature setting threshold for turning on cooling, the temperature sensitive switch 212 may change states to a cooling state. In the cooling state, the A/C controller 210 may apply a 24VAC (volts of alternating current) power source between the yellow wire 224 and the red wire 221. In some embodiments, the A/C controller 210 may also apply power between the green wire 222 and the red wire 221 to turn on the fan 270. In other embodiments, the A/C controller 210 may comprise different color wires and, in further embodiments, the A/C controller 210 may comprise different controller logic that may require a different wiring scheme. For instance, in some embodiments, components may be added and/or some components may be bypassed or modified to implement an embodiment of the invention.

In further embodiments, the A/C controller 210 may comprise other user settings such as a humidity setting. The A/C controller 210 may initiate cooling, heating, and/or dehumidification based upon the humidity setting and/or other settings.

Turning on the cooling may involve applying power such as a 24VAC power source to a yellow wire 224 to instruct the fan controller 260 to turn on the fan 270 at a high fan speed. In some embodiments, the yellow wire 224 may couple with the temperature sensor 240 and the temperature sensor may couple with the fan switch 250 to apply, e.g., 24VAC to the relay coil of the fan switch 250 or remove 24VAC from the coil of the fan switch 250 based upon the actions of the temperature sensor 240 and the measurements of temperature by the thermometer 241 of the temperature sensor 250. In some embodiments, the temperature sensor 250 comprises only the thermometer 241. In other embodiments, the temperature sensor 250 also comprises other supportive circuitry or connectors such as one or more transistors.

In several embodiments, the yellow wire 224 may apply 24VAC to a first input terminal 248 of the logic 247. In the present embodiment, the logic 247 is coupled with the temperature sensor 240 to monitor the temperatures sensed by the thermometer 241. In other embodiments, the logic 247 may be couple in series with temperature sensor 240 or in parallel with the temperature sensor 240.

In the present embodiment, the logic 247 may be a distinct device from the temperature sensor 240. In other embodiments, the logic 247 may be part of the temperature sensor 240, part of the A/C controller 210, part of the fan controller 260, or part of another device. Thus, in the current embodiment, the terminals 244 may be connected via wires or other conductive interconnections 246 to couple the logic 247 with the temperature sensor 240.

The temperature sensor 240 may comprise the thermometer 241 coupled with the return line of the air conditioning system between the evaporative unit and the condenser unit such as is illustrated in FIG. 1. The temperature sensor 240 may cycle between a first sensor state and a second sensor state based upon a high temperature threshold and a low temperature threshold, may have a distinct number of states dependent upon the temperature of the return line, or may have a continuous variation of a characteristic or quality such as a resistance that varies with the temperature of the return line. In other embodiments, the temperature sensor 240 may comprise a temperature switch such as a bi-metallic switch, a bulb-type switch, a thermocouple, a solid state temperature switch, an integrated circuit comprising a temperature sensor, or other temperature sensor that changes states in response to the temperature it is measuring.

In further embodiments, a heat generator may be located proximate to the temperature switch and may be in series with the adjustable resistance via the second input terminal via the red wire 221 from the A/C controller 210 to adjust heat applied to the temperature switch. Other embodiments, rather than comprising or in addition to comprising the adjustable resistance, may comprise an adjustable impedance to adjust current to the heat generator, a current limiting element or device to adjust current to the heat generator, a voltage adjustment element or device to adjust the voltage across terminals of the heat generator, and/or the like.

The application of heat may increase the switching speed of the temperature switch by more quickly raising the temperature switch to a target switching temperature. The application of heat to the temperature switch may also raise the high threshold temperature and the low threshold temperature for switching between sensor states.

In some embodiments, the temperature sensor 240 may measure temperature and the logic 247 may determine the points at which the power to the relay coil of the fan switch 250 will be turned on or turned off. For instance, if the temperature sensed by the thermometer 241 indicates a threshold temperature, the logic 247 may change the state of the power applied to the relay coil of the fan switch 250 accordingly. In further embodiments, the logic 247 may determine the state of the power applied to the relay coil of the fan switch 250 based upon other considerations in addition to the temperature sensed by the temperature sensor 250.

Other embodiments of temperature sensor 240 may include a solid-state temperature sensor. In further embodiments, the heat generator may generate heat and may apply the heat via conduction, convection, and/or radiation to the bi-metallic switch in response to a change in state of the temperature switch to reduce lag time associated with hysteresis for switching between states.

In some embodiments, the logic 247 may monitor the state of the temperature sensor 240 and may override the operation of the temperature sensor 240 by closing the circuit between the yellow wire 224 and terminal 251 of the fan switch 250. In particular, the logic 247 may monitor the temperatures of a low pressure side return line of an air conditioning system such as the system 100 in FIG. 1 to determine a duty cycle for the fan 270.

In some embodiments, the logic 247 determines a “second fan state” time, which may also be referred to as a fan-off time when the second fan state is an off state of the fan 270. In many embodiments, the logic 247 comprises a timing circuit to measure passage of time to determine the second fan state time. In other embodiments, the logic 247 may couple with a timing circuit such as a clock circuit to measure the passage of time.

The optimal second fan state time a calculation of, measurement of, and/or an approximation of the amount of time that the fan 270 should remain in the second fan state or off to let the cooled coolant to enter the evaporative coil. The second fan state time is the amount of time that passes after the fan 270 is in the second fan state before a noticeable or threshold temperature change occurs at the temperature sensor 240 on the return line. For example, an efficient time frame for leaving the fan off may in a range between 20 and 35 seconds. While the fan 270 is off, the coolant may cool by about 17° F. from about 80° F. to 63° F. By the time the cooled coolant reaches the return line, the cooled coolant is returning the to compressor, degrading the efficiency of the system. So the logic 247 may determine that the cooled coolant reaches the temperature switch at 30 seconds from the time the fan is turned off (the second fan state time or fan-off time) and, in response, turn on the fan, in a subsequent cycle, ten seconds earlier or at 20 seconds from the time the fan was turned off (the optimal second fan state time or optimal fan-off time).

The second fan state times may depend upon the air conditioning system cycle, the coolant in use, and environmental conditions and the logic 247 may adjust the second fan state time to maintain the system near or at a selected second speed time or within a range of time periods by adjusting the second fan state time based upon temperature readings from the temperature sensor and the timing of the temperature readings from the temperature sensor. For example, the selected fan-off time may be around 20 seconds, which may be selected by default or by a setting via, e.g., a dip switch. Depending upon the air conditioning system and other factors, the selected fan-off time may be in a range between 15 and 25 seconds, between 10 and 30 seconds, or between 10 and 40 seconds. Furthermore, the selected drop in temperature at the return line may be in a range between 5° F. and 17° F., between 8° F. and 15° F., or be at or around 12° F. So the logic 247 may default to selection of a 70% or 75% of the fan-off time prior to turning on the fan as a manufacturer setting. When the fan is turned off, the logic 247 may measure the time between system turning off the fan and the return line dropping, e.g., 12° F. The fan will be turned on in response to the temperature dropping 12° F. or reaching a low temperature threshold. Then the fan-off time measured will be reduced to about 70% of the measured fan-off time to determine the optimal fan-off time.

The reduction of the fan-off time will cause the fan to force air across the evaporative coils prior to the cooled coolant traveling completely through the coils to the return line. The logic 247 may then monitor the timing of the drop in the temperature of the coolant in the return line. For example, the cooled coolant may reach the return line 12 seconds after the fan 270 is turned on. Based upon this determination, the logic 247 may adjust the fan-off time by a couple seconds by energizing the coil of fan switch 250 prior to temperature sensor 240 changing states so that the drop in temperature of the coolant at the return line occurs 10 seconds after the fan 270 is turned on. In some embodiments, the logic 247 may select a fan-off time or second fan state time based upon the timing of the temperature drop of the return line as measured via the timing circuit 248.

In further embodiments, the logic 247 may take into consideration the temperature drop at the return line in addition to the amount of time between turning on the fan and the temperature drop. For instance, the logic 247 may determine that at 12 seconds from turning on the fan 270, the return line drops by 8° F. rather than 12° F. due to the reduction in the fan-off time. The logic 247 may employ an algorithm to find a desired balance between the timing of the drop in temperature and the temperature drop such as, e.g., 10 seconds and 12° F. Such an algorithm may estimate a second fan state time or fan-off time once, continue to estimate the time based upon the current timing and temperature drop, or refine the estimate based upon the current timing and temperature drop and one or more prior timings and temperature drops.

In several embodiments, the logic 247 may maintain the timing of the drop in temperature at the return line after the fan 270 is turned on and the temperature drop at the return line within a range. In other embodiments, the logic 247 may maintain the timing of the temperature drop within a time range rather than both the timing and the temperature drop. In still other embodiments, the logic 247 may maintain the temperature drop at the return line within a range rather than both the timing and the temperature drop.

The fan switch 250 may comprise a relay. In some embodiments, the relay of the fan switch 250 may comprise a relay coil. In the present embodiment, the output terminal 249 of the logic 247 may couple with the first input terminal 251 to apply the 24VAC power to an inductor of the relay via the first input terminal 251 and the red wire 221 of the A/C controller 210. The inductor is in an energized state when power is applied to the inductor and is in a de-energized state when power is disconnected from the inductor. Switching between the energized state and the de-energized state changes the state of a switch of the fan switch 250. The fan switch 250 may have two states, an open circuit state and a closed circuit state. The open circuit state may open the circuit between terminal 254 and terminal 255 of the fan switch 250 and the closed circuit state may close the circuit between terminals 254 and 255. In the present embodiment, closing the circuit between terminals 254 and 255 applies power to the fan 270 if the fan 270 is turned on by the A/C controller 210. Opening the circuit between terminals 254 and 255 disconnects the power from the fan 270.

In other embodiments, fan switch 250 may be part of fan controller 260. For instance, in some embodiments, the fan switch 250 may be installed on a control circuit 262 circuit board of fan controller 260. In some embodiments, fan switch 250 may be a solid-state relay instead of the inductor type relay described above. Further embodiments may comprise a different type of switch.

Fan controller 260 may couple with wiring 221-224 from A/C controller 210 to turn on the fan 270 in response to a signal from A/C controller 210 instructing fan controller 260 to turn on the fan 270. In some embodiments, the fan 270 may have more than one speed. In such embodiments, the fan switch 250 via terminals 254 and 255, may be interconnected between the fan controller 260 and the fan 270 via a conductor that applies power to fan 270 to turn on fan 270 at a high fan speed. The high fan speed may thus be turned on and off based upon the temperature sensed by temperature sensor 240. In further embodiments, terminals 254 and 255 may be coupled between other conductors of fan 270 to turn on fan 270 at a different fan speed. In other embodiments, the fan switch 250 may couple between the fan controller 260 and fan 270 to switch between more than one speeds of fan 270. For instance, fan switch 250 may switch between a first fan speed and a second fan speed in response to a state change of the temperature sensor 240.

In other embodiments, the fan switch 250 may be coupled with the control circuit 262 of fan controller 260 to turn on and off a fan speed or to switch the fan 270 between a high fan speed and a low fan speed. In still other embodiments, temperature sensor 240 may be coupled with a switch in fan controller 260 rather than or in addition to the logic 247 and the fan switch 250.

FIG. 3 depicts an embodiment of an installed apparatus to switch a fan 330 of an air conditioning system 300 between two fan speed states. The apparatus comprises a housing 340 and a heat sink 350 clamped to the low side tubing 370 for the return line for a low-pressure coolant vapor 360 via clamps 352 and 354. In some embodiments, the housing 340 may comprise a temperature sensor 344 and a relay 348. In the present embodiment, the housing 340 also comprises logic 346. The temperature sensor 344 may sense a current temperature of the coolant vapor 360 via the heat sink 350 and the low side tubing 370. Based upon the current temperature, changes in the current temperature, and/or timing of changes in the current temperature; the relay 348 may open and close a circuit between the a/c controller 310 and the fan 330, effectively switching the fan 330 between a first fan state and a second fan state for periods of time during which the a/c controller 310 is applying power to the fan 330 via a/c controller power conductors 320. For instance, the second fan state may be an off state and the relay 348 may switch the fan 330 on and off via an 110 VAC, on/off signal 335 based upon temperatures sensed by the temperature sensor 344.

In the present embodiment, the logic 346 may receive a heater signal 315 as an input and may not cycle the fan 330 on and off while the heater is turned on by the a/c controller 310 as indicated by the, e.g., 24 VAC, heater signal 315. In many embodiments, the logic 346 may minimize hysteresis associated with turning on and off the fan 330 based upon threshold temperatures and, in some embodiments, the logic 346 may determine the temperature thresholds for changing the states of the fan 330. In several embodiments, the logic 346 may comprise logic to protect the fan 330 or to increase or maximize the efficiency of the fan 330. In further embodiments, the logic 346 may comprise a timing circuit to minimize hysteresis for changing the state of the fan 330, protecting the fan 330, and/or increasing or maximizing the efficiency of the fan 330. In still further embodiments, the logic 346 may perform other functionality discussed in relation to other embodiments disclosed herein.

FIG. 4 depicts an alternative embodiment of an installed apparatus to switch a fan 430 of an air conditioning system 400 between three fan speed states. The difference between FIG. 3 and FIG. 4 is that the fan 330 is a two-speed fan and fan 430 is a three-speed fan. The logic 446 may determine when to change between three different states based upon the temperatures sensed by temperature sensor 344 and may output a high speed signal 432 and a low speed signal 437 to switch between, e.g., a high speed fan state, a low speed fan state, and an off state. In further embodiments, the logic 446 may perform other functionality discussed in relation to other embodiments disclosed herein.

FIG. 5 illustrates an embodiment 500 of a flow chart for cycling the blower of an air conditioning system such as the air conditioning system of FIG. 1. The embodiment begins with receiving, from an air conditioner controller, a signal to turn on a fan (element 510). The signal may comprise a digital signal, the application of power to a wire, the opening or closing of a circuit coupled with a wire, the application of a light signal on a optical fiber or the like. In many embodiments, the signal may also indicate the initiation of a cooling cycle of the air conditioning system.

A temperature sensor may concurrently determine a temperature related to a low-pressure coolant in a return line between an evaporative unit of the air conditioning system and a condenser unit of the air conditioning system (element 520). In many embodiments, determining the temperature comprises determining a magnitude of current through a temperature-sensitive resistance of a temperature sensor. In several embodiments, determining the temperature comprises measuring the temperature with a solid-state circuit of a temperature sensor. In some embodiments, determining the temperature comprises switching, by a bi-metallic switch of a temperature sensor, between a first switch state and a second switch state. Further embodiments comprise applying heat to the temperature sensor in response to receiving the signal. Such embodiments may comprise adjusting a current applied to a heater unit in proximity of the temperature sensor to adjust the low threshold temperature and the high threshold temperature and to adjust a switching speed of the temperature sensor.

In a number of embodiments, the low threshold temperature and the high threshold temperature are the same temperature. Some of these embodiments may include a time delay that is inherent to the temperature switch or that is purposely incorporated, e.g., via a delay circuit, a mechanical delay device, or another delay device.

In other embodiments, determining the temperature comprises switching, by solid-state switch, between a first switch state and a second switch state. In such embodiments, determining the temperature may comprise measuring a resistance of a thermistor, measuring the voltage of a thermocouple, or measuring the output signal of a temperature sensing integrated circuit in contact with the return line or measuring a resistance of a thermistor, measuring the voltage of a thermocouple, or measuring the output signal of a temperature sensing integrated circuit in contact with the coolant in the return line. In further embodiments, determining the temperature comprises switching, by bulb-type switch, between a first switch state and a second switch state.

Upon receiving the signal and determining the state of the temperature sensor, a fan switch may switch power applied to the fan to change a fan speed of the fan from a high speed fan state to a second fan state in response to determining or anticipating when the temperature reaches a low threshold temperature and to change the fan speed from the second fan state to the high speed fan state in response to determining or anticipating when the temperature reaches a high threshold temperature (element 530). In many embodiments, switching the power applied may comprise switching between a first switch state and a second switch state. In several embodiments, the switching may be based upon the current temperature measurement via the return line and, in some of these embodiments, the switching may also be based upon a time delay or hysteresis implemented in the switching circuit.

In further embodiments, the temperature sensor may couple with logic for switching the power applied to the fan. For instance, some embodiments may determine when to switch the power based upon a time elapsed since changing the fan state, the temperature at the return line, the amount of the temperature drop since changing the fan state, or some combination thereof.

In several embodiments, the logic may determine when to switch power based upon the current temperature and one or more previous temperature measurements and/or time measurements. For instance, the logic may comprise or couple with a timing circuit. The timing circuit may count or indicate a passage of time in units and the logic may utilize the passage of time between changing the state of the fan and a drop in temperature at the return line to determine when to change the state of the fan again between the first and second fan states or between more than two different fan states.

In some embodiments, the logic may minimize hysteresis or adjust temperature thresholds to reduce the time between changing the state of the fan from the first fan state to the second fan state and/or vice versa. In further embodiments, the logic may ensure that a minimum time elapses between changes in the state of the fan to protect the fan motor from, e.g., overheating and/or to improve the efficiency of the fan.

In some embodiments, switching the power applied may comprise switching between a first switch state that is an open switch state in which the bi-metallic switch opens a circuit, and a second switch state that is a closed switch state in which the bi-metallic switch closes a circuit. In other embodiments, switching the power applied may comprise switching between the first switch state that is a closed switch state in which the bi-metallic switch closes a first circuit, and the second switch state that is a closed switch state in which the bi-metallic switch closes a second circuit.

In some embodiments, the fan switch may switch power applied to the fan to change a fan speed of the fan from a high speed fan state to a second fan state in response to anticipating when the temperature reaches a low threshold temperature and to change the fan speed from the second fan state to the high speed fan state in response to anticipating when the temperature reaches a high threshold temperature (element 530). For instance, the logic may anticipate the change in temperature to a low threshold temperature or a high threshold temperature by determining the second fan state time, switching the power after a second fan state time elapses while in the second fan state, determining a change in the temperature that precedes a change to the low threshold temperature or to the high threshold temperature, or the like.

In many embodiments, switching the power applied to the fan comprises changing a state of a relay between a first relay state and a second relay state. Changing the state of the relay may comprise changing the state of a transistor of a solid-state relay or changing the state of a coil of an inductor-type relay between an energized coil state and a de-energized coil state. In further embodiments, changing the state of the relay may comprise changing the state of multiple relays. For instance, relays may be coupled in series and/or parallel to accomplish speed adjustments of the fan. In some embodiments, a first relay may change the state of a second relay coupled in series with the first relay and changing the state of the second relay may open or close motor contacts of the fan. In some embodiments, more than one relay may operate in parallel to open motor contacts of the fan. In several embodiments, a first relay may comprise the motor contacts and changing states of the first relay may change the state of the motor contacts.

In many embodiments, the motor contacts of the fan are contacts of a motor relay in a motor control circuit. In some embodiments, the fan switch is the motor relay. In other embodiments, the fan switch has contacts in the series or in parallel with contacts of the motor relay in the motor control circuit. In further embodiments, the fan switch couples with the motor relay to change the state of the motor relay.

Furthermore, switching power applied to the fan may comprise switching the fan on at a high speed to place the fan in the high-speed fan state and switching the fan off to place the fan in the second fan state. In other embodiments, switching power applied to the fan may comprise switching the fan on at a high speed to place the fan in the high-speed fan state and switching the fan on at a low speed to place the fan in the second fan state. In further embodiments, switching power applied to the fan may comprise switching the power applied to the fan via a module that is clamped onto the low pressure side return line, wherein the module comprises both a temperature sensing device and a fan switch. In some of these embodiments, determining the temperature and switching the power applied to the fan comprises determining the temperature and switching the power applied to the fan via a thermometer element and a solid-state relay residing on a single integrated circuit of the module. In other embodiments, the thermometer element and the solid-state relay may reside on separate integrated circuits in the module.

After determining an initial timing and temperature drop, the present embodiment 500 may optionally determine a duty cycle (element 540). In other embodiments, the duty cycle may be set by default and may be adjusted thereafter, may be set by a technician based upon factors or characteristics associated with the air conditioning system, or may be set by a technician or by default and adjusted thereafter by the logic. The factors or characteristics may comprise the type of air conditioning cycle, the environmental conditions or climate about the air conditioning system, the geographical region in which the air conditioning system is installed, the type of coolant, the coolant capacity of the air conditioning system, the specification of components of the cooling system (such as the evaporative unit, the expansion valve, the compressor, the compressor coils, or the like), or other factors.

Determining the duty cycle (element 540) may comprise determining the second fan state time such as the fan-off time, the high speed state time (the amount of time during which the fan is in a high speed state), a percentage of time during which the fan should remain the high speed state or the second fan state, the temperature changes that cause a change in states, or the like. In some embodiments, determining the duty cycle (element 540) may comprise selecting a duty cycle based upon a temperature change and/or a timing of the temperature change with respect to placing the fan in a second fan state. In several embodiments, selecting a duty cycle may comprise selecting a duty cycle from a library of duty cycles. In further embodiments, determining a duty cycle (element 540) comprises selecting a duty cycle based upon a brand of the air conditioning system, a type of cycle of the air conditioning system, a cooling capacity of the air conditioning system, or another characteristic of the air conditioning system.

In further embodiments, determining a duty cycle (element 540) may comprise determining a duty cycle with an algorithm based upon a temperature change and/or a timing of the temperature change with respect to placing the fan in a second fan state. In still other embodiments, determining a duty cycle (element 540) may comprise determining a setting of a dip switch or a configuration of other hardware or the value of a setting in a memory coupled with the logic. In many embodiments, determining a duty cycle (element 540) may comprise determining a default duty cycle set by a manufacturer or designer of the logic.

After determining a duty cycle (element 540), the present embodiment 500 optionally comprises cycling the fan based upon the duty cycle (element 550). Cycling the fan based upon the duty cycle (element 550) may comprise switching power applied to the fan to change the fan speed based upon the duty cycle. For example, the duty cycle may be defined by cycle time periods such as cycling the fan speed to a high speed fan state for 40 seconds of every minute and to second fan state for 20 seconds of every minute. In other embodiments, the fan speed may be cycled to the high speed fan state for 30 seconds of each minute and to the fan off state for 30 seconds out of every minute. In further embodiments, the fan speed may be cycled from a first fan state to a second fan state for 15 seconds of every minute or 25 seconds of every minute.

In many embodiments, the logic may adjust the duty cycle one or more times based upon the timing of a change in temperature toward or to a low threshold temperature and/or the change in the temperature. In further embodiments, the logic may adjust the duty cycle one or more times based upon the timing of a change in temperature toward or to a high threshold temperature and/or the change in the temperature.

Note that temperature sensing devices and temperature sensors, in many embodiments, refer to devices that can sense a change in a relative temperature and within a range of temperatures. The temperature measured or determined may be a change in a characteristic of the temperature sensing device or sensor such as a change in resistance, a change in impedance, a change in voltage drop across the device or sensor, a change in the current through the device or sensor, the change in the voltage or current produced by the device or sensor, or the like. In such embodiments, a reference temperature may be determined in the design or in the fabrication of the device or sensor or the embodiment but may or may not be compared with the characteristic of the device or sensor thereafter during normal operation. In other embodiments, a reference may be included in the embodiment and compared with readings or measurements from the device or sensor to determine or monitor an absolute temperature rather than a relative temperature change.

FIG. 6 illustrates an embodiment 600 of a flow chart for installing a retrofit for cycling the blower of an air conditioning system. The embodiment 600 begins with installing a temperature sensor optionally with logic on a return line between an evaporative unit and a condenser unit, wherein the return line returns a coolant exiting the evaporative unit to the condenser unit (element 610). Installing the temperature sensor may comprise coupling the temperature sensor or temperature sensing device with the return line to place the temperature sensor in contact with the return line or coupling the temperature sensor with the return line to place the temperature sensor in contact with the coolant in the return line. The temperature sensor, in many embodiments, is coupled with the return line via a heat sink.

Coupling the temperature sensor with the return line may involve clamping a module comprising the temperature sensor and a heat sink to the return line. In such embodiments, the module may be clamped on the return line in such a way as to place contacts of the temperature sensor in contact with the return line or in contact with the heat sink. If the temperature sensor is in contact with the heat sink, the temperature sensor may be calibrated accordingly to account for the temperature drop across the heat sink. In other embodiments, the logic may be installed separately and coupled with the temperature sensor.

Installing the temperature sensor may also comprise coupling the temperature sensor with the logic. In such embodiments, the temperature sensor and the logic may comprise two distinct components. In other embodiments, the temperature sensor and the logic may be fabricated as a single, integrated product wherein the logic is coupled with the temperature sensor.

Embodiment 600 continues with coupling a signal wire to the temperature sensor, the signal wire communicatively coupled with an air conditioner controller for transmitting a signal from the air conditioner controller to a fan controller to turn on the fan (element 620). In some embodiments, coupling the signal wire to the temperature sensor with logic comprises coupling a yellow wire of the air conditioner controller with a first terminal of the temperature sensor. In other embodiments, coupling the signal wire to the temperature sensor may comprise coupling another wire of the air conditioner controller with a first terminal of the temperature sensor or with a different terminal of the temperature sensor. In further embodiments, the logic may be wired in parallel or in series with the temperature sensor. In some embodiments, a heat cycle signal wire may be coupled with the logic and/or the temperature sensor to avoid cycling the fan when the heat cycle is activated by the air-conditioner controller.

Embodiment 600 continues with coupling the temperature sensor with a relay (element 630). Coupling the temperature sensor with the relay (element 630) may facilitate switching the power applied to the fan. Coupling the temperature sensor with the relay (element 630) may also comprise coupling a second terminal of the temperature sensor with the relay such that the logic can override the output based upon the temperature to anticipate a drop in the temperature. For instance, the relay may reside in a fan controller or may be installed near the fan controller or with the temperature sensor near or on the return line. In some embodiments, coupling the temperature sensor with the relay may be performed at a manufacturing facility. For instance, coupling the temperature sensor with the relay may comprise coupling the temperature sensor with the relay on an integrated circuit, coupling two integrated circuits, coupling an integrated circuit with the temperature sensor, coupling the integrated circuit with the relay, coupling the integrated circuit with both the temperature sensor and the relay, or the like. In such embodiments, the temperature sensor and the relay may reside in a package such as a module such as a box and the box may include terminals to interconnect the relay with the fan controller or between the fan controller and the fan as well as terminals to interconnect the package with an air conditioner controller. In many embodiments, the module is clamped to the low side, return line. In some of these embodiments, the action of clamping the module to the low side, return line places a temperature sensing device in contact with the return line. In other embodiments, additional action may be taken to place the temperature sensor or contacts of the temperature sensor in contact with the return line via a heat sink.

Embodiment 600 continues with coupling the relay with the fan controller to switch between a first fan speed state and a second fan speed state (element 640). In several embodiments, coupling the relay with the fan controller comprises coupling a switch of the relay to connect power to or disconnect power from a terminal of the fan controller, wherein connecting power to and disconnecting power from the terminal changes the fan between the first fan state and the second fan state. In further embodiments, coupling the relay with the fan controller comprises coupling a switch of the relay to connect power to a first terminal of the fan controller or a second terminal depending upon a state of the relay, wherein connecting power to the first terminal and then connecting power to the second terminal changes the fan from the first fan state to the second fan state.

Another embodiment is implemented as a computer program product for implementing systems and methods described with reference to FIGS. 1-6. Embodiments can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment containing both hardware and software elements. Entirely hardware embodiments may comprise state machines to perform logic or portions of logic. One embodiment is implemented in software, which includes but is not limited to firmware, resident software, microcode, etc. Such code may be executed by one or more processors, microcontrollers, or the like.

Furthermore, embodiments can take the form of a computer program product accessible from a computer-usable or computer-readable medium providing program code for use by or in connection with a computer or any instruction execution system. For the purposes of this description, a computer-usable or computer readable medium can be any apparatus that can store or propagate the program for use by or in connection with the instruction execution system, apparatus, or device. A tangible, computer-usable, computer-accessible, or computer-readable medium can be any apparatus that can store the program on a tangible medium in a tangible way.

The computer-usable or computer-readable medium can be an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system (or apparatus or device) or a propagation medium. Examples of a tangible computer-readable medium include tangible media such as a semiconductor or solid-state memory, magnetic tape, a removable computer diskette, a random access memory (RAM), a read-only memory (ROM), a rigid magnetic disk, and an optical disk. Current examples of optical disks include compact disk-read only memory (CD-ROM), compact disk-read/write (CD-R/W), and DVD.

A data processing system suitable for storing and/or executing program code will include at least one processor coupled directly or indirectly to memory elements through a system bus. The memory elements can include local memory employed during actual execution of the program code, bulk storage, and cache memories which provide temporary storage of at least some program code in order to reduce the number of times code must be retrieved from bulk storage during execution.

Input/output or I/O devices (including but not limited to keyboards, displays, pointing devices, etc.) can be coupled to the system either directly or through intervening I/O controllers. Network adapters may also be coupled to the system to enable the data processing system to become coupled to other data processing systems or remote printers or storage devices through intervening private or public networks. Modems, cable modem, and Ethernet adapter cards are just a few of the currently available types of network adapters.

The logic as described above may be part of the design for an integrated circuit chip. The chip design is created in a graphical computer programming language, and stored in a computer storage medium (such as a disk, tape, physical hard drive, or virtual hard drive such as in a storage access network). If the designer does not fabricate chips or the photolithographic masks used to fabricate chips, the designer transmits the resulting design by physical means (e.g., by providing a copy of the storage medium storing the design) or electronically (e.g., through the Internet) to such entities, directly or indirectly. The stored design is then converted into the appropriate format (e.g., GDSII) for the fabrication of photolithographic masks, which typically include multiple copies of the chip design in question that are to be formed on a wafer. The photolithographic masks are utilized to define areas of the wafer (and/or the layers thereon) to be etched or otherwise processed.

The resulting integrated circuit chips can be distributed by the fabricator in raw wafer form (that is, as a single wafer that has multiple unpackaged chips), as a bare die, or in a packaged form. In the latter case, the chip is mounted in a single chip package (such as a plastic carrier, with leads that are affixed to a motherboard or other higher level carrier) or in a multichip package (such as a ceramic carrier that has either or both surface interconnections or buried interconnections). In any case, the chip is then integrated with other chips, discrete circuit elements, and/or other signal processing devices as part of either (a) an intermediate product, such as a motherboard, or (b) an end product. The end product can be any product that includes integrated circuit chips, ranging from toys and other low-end applications to advanced computer products having a display, a keyboard or other input device, and a central processor.

Alternately the control logic may be resident elsewhere and communicate with the A/C via Bluetooth® or other of the many systems for remote control of appliances, garage doors, A/C etc.

Similarly a remote control, as are now commonly used with window A/C units, may be used to communicate with the A/C and the control logic could be placed in the remote device, in a controller of the A/C unit or partially in the remote device and partially in a controller of the A/C unit.

It will be apparent to those skilled in the art having the benefit of this disclosure that the present disclosure contemplates air-conditioning with dehumidification. It is understood that the form of the embodiments shown and described in the detailed description and the drawings are to be taken merely as examples. It is intended that the following claims be interpreted broadly to embrace all variations of the example embodiments disclosed.

Although the present disclosure has been described in detail for some embodiments, it should be understood that various changes, substitutions, and alterations could be made herein without departing from the spirit and scope of the disclosure as defined by the appended claims. Although specific embodiments may achieve multiple objectives, not every embodiment falling within the scope of the attached claims will achieve every objective. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods, and steps described in the specification. As one of ordinary skill in the art will readily appreciate from this disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps. 

1. A method comprising: receiving, from an air conditioner controller, a signal to turn on a fan; monitoring a temperature by a temperature sensor coupled with a low pressure side return line for a low-pressure coolant between an evaporative unit and a condenser unit; and switching power applied to the fan to change the fan speed of the fan from a high speed fan state to a second fan state based upon the signal from the air conditioner controller and monitoring the temperature.
 2. The method of claim 1, further comprising determining a second fan state time, wherein determining the second fan state time comprises determining an amount of time to leave the fan in the second fan state to allow cooled coolant from the condenser unit resulting from the fan being in the second fan state to build up in the evaporative unit but not leave the evaporator coils while still cold.
 3. The method of claim 2, wherein determining an amount of time to leave the fan in the second fan state to allow cooled coolant from the condenser unit to enter the evaporative unit comprises estimating an amount of time to leave the fan off.
 4. The method of claim 2, wherein determining an amount of time to leave the fan in the second fan state to allow cooled coolant from the condenser unit to enter the evaporative unit comprises determining the amount of time based upon measuring an amount of time between changing the fan speed from the high speed fan state to the second fan state and receiving an indication of the change in the state of the fan speed via a subsequent temperature related to the low-pressure coolant in the low pressure side return line between the evaporative unit and the condenser unit.
 5. The method of claim 4, wherein the amount of time based upon measuring comprises setting an optimal second fan state time to between ten and fifteen seconds less than the amount of time to leave the fan off to allow cooled coolant from the condenser unit to pass completely through the evaporative unit still cold and partly still liquid.
 6. The method of claim 4, wherein determining the amount of time based upon measuring comprises setting an optimal second fan state time to between seventy percent and seventy-five percent of the amount of time to leave the fan off to allow cooled coolant from the condenser unit to pass completely through the evaporative unit still cold and partly still liquid.
 7. The method of claim 1, further comprising determining an optimal second fan state time by adjusting a second fan state time based upon temperature readings from a temperature sensor at the low pressure side return line and the timing of changes to temperature readings from the temperature sensor in relation to changes in the state of the fan speed of the fan.
 8. The method of claim 7, wherein determining the optimal second fan state time further comprises determining the optimal second fan state time to be a time period during which the temperature related to the coolant in the low pressure side return line drops by threshold temperature change.
 9. The method of claim 7, wherein determining the optimal second fan state time further comprises determining the optimal second fan state time to be a time period during which the temperature related to the coolant in the low pressure side return line resides within a predetermined temperature range.
 10. The method of claim 7, wherein determining the optimal second fan state time further comprises determining the optimal second fan state time to be less than the second fan state time the by a predetermined amount of time or a predetermined proportion of time.
 11. The method of claim 7, wherein determining the optimal second fan state time further comprises determining the optimal second fan state time by employing an algorithm to determine the optimal second fan state time based upon a balance between a temperature drop at the temperature sensor on the low pressure side return line and a timing of a drop in temperature at the temperature sensor on the low pressure side return line.
 12. The method of claim 1, wherein monitoring the temperature and switching the power applied comprises monitoring the temperature via a bi-metallic switch, wherein the bi-metallic switch switches between a first switch state and a second switch state in response to a threshold temperature, wherein switching between the first switch state and the second switch state in response to the threshold temperature changes the fan speed of the fan from the high speed fan state to the second fan state.
 13. The method of claim 12, further comprising applying heat to the bi-metallic switch in response to a change in state of the switch to reduce hysteresis lag time.
 14. The method of claim 1, wherein monitoring the temperature and switching the power applied to the fan comprises determining the temperature and switching the power applied to the fan via a thermometer element and a solid-state relay residing on a single integrated circuit of the module.
 15. An apparatus comprising: a housing adapted to couple with a low pressure side return line between an evaporative unit and a condenser unit, the housing comprising: a temperature sensor to determine a temperature related to a low-pressure coolant in the return line; and a relay coupled with the temperature sensor to change a fan speed of a fan from a high speed fan state to a second fan state based upon a temperature indicated by the temperature sensor.
 16. The apparatus of claim 15, wherein the housing further comprises logic to couple with the temperature sensor to monitor the temperature related to the low-pressure coolant in a low pressure side return line between the evaporative unit and the condenser unit to determine when to change the fan speed of the fan from a high speed fan state to a second fan state based upon monitoring the temperature related to the low-pressure coolant in the return line.
 17. The apparatus of claim 16, wherein the logic comprises an output to output a signal to the relay to place the fan in a high speed fan state after the temperature falls below 40 degrees Fahrenheit.
 18. The apparatus of claim 16, wherein the logic comprises an output to output a signal to the relay to place the fan in a high speed fan state in response to a signal from an air conditioner controller indicating that a heater is on.
 19. The apparatus of claim 15, wherein the housing further comprises logic to couple with the temperature sensor to monitor the temperature related to the low-pressure coolant in a low pressure side return line between the evaporative unit and the condenser unit to minimize hysteresis involved with changing the fan speed of the fan from a high speed fan state to a second fan state based upon monitoring the temperature related to the low-pressure coolant in the return line.
 20. The apparatus of claim 15, wherein the housing further comprises logic to couple with the temperature sensor to monitor the temperature related to the low-pressure coolant in a low pressure side return line between the evaporative unit and the condenser unit to protect the fan from damage when repeatedly changing the fan speed of the fan between a high speed fan state and a second fan state.
 21. The apparatus of claim 15, wherein the housing further comprises logic to couple with the temperature sensor to monitor the temperature related to the low-pressure coolant in a low pressure side return line between the evaporative unit and the condenser unit to increase an efficiency of the fan when changing the fan speed of the fan between a high speed fan state and a second fan state by reducing a ratio between an amount of time that the fan is in the high speed fan state and an amount of heat transferred from air to the coolant.
 22. The apparatus of claim 15, wherein the housing further comprises logic to couple with the temperature sensor to monitor the temperature related to the low-pressure coolant in a low pressure side return line between the evaporative unit and the condenser unit to determine a duty cycle for the fan to change the fan speed of the fan from a high speed fan state to a second fan state based upon monitoring the temperature related to the low-pressure coolant in the return line.
 23. The apparatus of claim 15, wherein the temperature sensor comprises a bi-metallic switch to switch between a first switch state and a second switch state based upon the temperature related to the low-pressure coolant in the return line.
 24. The apparatus of claim 15, wherein the temperature sensor comprises at least one of a group of temperature sensing devices comprising a solid-state temperature sensor, a thermistor, a solid state switch to switch between one or more states based upon a temperature of the return line, and an integrated circuit with a switch to switch between an first switch state and a second switch state based upon the temperature of the return line.
 25. The apparatus of claim 15, wherein the logic comprises a timing circuit to learn an average second fan state time.
 26. The apparatus of claim 25, wherein the average second fan state time is an average fan-off time, the fan off time being the time period between which the fan is turned off and a coolant temperature in the return line is determined to be cooled by a threshold temperature change at the temperature sensor.
 27. The apparatus of claim 25, wherein the logic comprises logic to shorten the average second fan state time by switching the fan on about 10 seconds earlier than when the temperature sensor senses that the low-pressure coolant in the return line has reached a low threshold temperature as a result of placing the fan in the second fan state.
 28. The apparatus of claim 25, wherein the logic comprises logic to shorten the average second fan state time by switching the fan to the high speed state between 25% to 30% earlier than when the temperature sensor senses that the low-pressure coolant in the return line has reached a low threshold temperature as a result of placing the fan in the second fan state.
 29. An system comprising: an air-handling unit comprising at least one cabinet to receive an incoming air flow and to output a conditioned, outgoing air flow, the at least one cabinet comprising: an evaporative unit to receive coolant from a condenser unit, wherein the air-handling unit directs the incoming air flow through the evaporative unit; a return line coupled with the evaporative unit to return low-pressure coolant to a compressor; at least one fan to force air flow through the evaporative unit; and a fan controller to adjust a speed of the fan to adjust the speed of the air flow through the evaporative unit; a temperature sensor to couple with the return line between the evaporative unit and the condenser unit to determine a temperature related to the low-pressure coolant in the return line; and a relay coupled with the temperature sensor to change the fan speed of the fan from a high speed fan state to a second fan state based upon the temperature related to the low-pressure coolant in the return line.
 30. The system of claim 29, further comprising logic to couple with the temperature sensor and the relay to monitor the temperature related to the low-pressure coolant in the return line between the evaporative unit and the condenser unit to determine when to change the fan speed of the fan from a high speed fan state to a second fan state based upon monitoring the temperature related to the low-pressure coolant in the return line.
 31. The system of claim 30, wherein the logic comprises a timing circuit to learn an average second fan state time, wherein the average second fan state time is an average fan-off time and wherein the logic shortens the average second fan state time by switching the fan on about 10 seconds earlier than when the temperature sensor senses that the low-pressure coolant in the return line has reached a low threshold temperature as a result of placing the fan in the second fan state.
 32. The system of claim 30, wherein the logic comprises a timing circuit to learn an average second fan state time and wherein the logic shortens the average second fan state time by switching the fan to the high speed state 25% earlier than when the temperature sensor senses that the low-pressure coolant in the return line has reached a low threshold temperature as a result of placing the fan in the second fan state.
 33. A method comprising: installing a temperature sensor on a return line between an evaporative unit and a condenser unit, wherein the return line returns a coolant exiting the evaporative unit to the condenser unit; coupling a signal wire to the temperature sensor, the signal wire communicatively coupled with an air conditioner controller for transmitting a signal from the air conditioner controller to a fan controller to turn on the fan; coupling a relay with the temperature sensor and the fan controller to switch between a first fan state and a second fan state based upon a temperature detected by the temperature sensor.
 34. The method of claim 33, wherein installing the temperature sensor comprises coupling the temperature sensor with the return line to measure the temperature of the return line.
 35. The method of claim 33, wherein installing the temperature sensor comprises coupling the temperature sensor with the return line via a heat sink. 